1. Field of the Invention
The present invention relates to an ink, an ink cartridge and an ink jet recording method.
2. Description of the Related Art
An ink jet recording method is such a recording method that minute droplets of an ink are applied to a recording medium such as plain paper to form an image, and is rapidly spread owing to low price of an apparatus itself and improvement of recording speed. In general, a recorded article obtained by the ink jet recording method is low in fastness properties of an image thereof compared with a silver salt photograph. In particular, when the recorded article is exposed to light, moisture, heat or environmental gas present in air, such as an ozone gas for a long period of time, there is a problem that a coloring material of the recorded article is deteriorated to easily cause change in color tone or fading of the image.
Since the change in color tone or fading of the image is caused especially by a cyan ink low in ozone resistance among respective inks of cyan, yellow and magenta as a main factor, there are a great number of proposals for improving the ozone resistance of the cyan ink. For example, there are proposals for improving the ozone resistance of an image by devising the structure of a phthalocyanine compound often used as a coloring material of the cyan ink (see International Publication No. 2004/087815 and International Publication No. 2007/091631).
As another problem in the cyan ink using the phthalocyanine compound, metallic luster, what is called a bronzing phenomenon, caused by high aggregation property of the phthalocyanine compound is mentioned. When the bronzing phenomenon is caused, the optical reflecting properties of the image are changed, and so the color developability and hue thereof look markedly poor to cause lowering of image quality. The bronzing phenomenon is considered to be caused by aggregation of the coloring material on the surface of a recording medium or in the neighborhood thereof due to the high aggregation property of the coloring material and lowering of permeability of an ink into the recording medium when the ink is applied to the recording medium. In order to inhibit the occurrence of the bronzing phenomenon, it has been proposed to add a polyhydric alcohol or an ether compound to an ink containing, for example, a copper phthalocyanine compound (see Japanese Patent Application Laid-Open No. 2005-350565).